Effects of Curcumin Supplementation on Production Performance, Intestinal Health and Cecal Microbiota in Late-Phase Jingfen No. 1 Laying Hens

This study investigated the effects of graded dietary curcumin supplementation on production performance, antioxidant capacity, immune status, intestinal barrier function, and cecal microbiota in late-laying hens. A total of 480 61-week-old Jingfen No. 1 laying hens were randomly allocated to four groups with six replicates of 20 birds each: a basal diet control (CG) and diets supplemented with 100, 200, or 400 mg/kg curcumin (CN1, CN2 and CN3) for 35 days. Curcumin supplementation significantly increased average egg weight (p < 0.05). Serum catalase concentration and immunoglobulin levels (IgM, IgA, and IgY) were elevated, whereas malondialdehyde, interleukin-6, interleukin-10, and tumor necrosis factor-α levels were reduced in a dose-dependent manner (p < 0.05). Similar improvements were observed in the jejunum, including increased glutathione peroxidase and catalase concentrations and reduced inflammatory cytokines. Birds in the CN3 group exhibited greater villus height and villus-to-crypt ratio, lower crypt depth, and upregulated mRNA expression of tight junction proteins (ZO-1, Occludin, and Claudin-1) (p < 0.05). Curcumin also modulated the cecal microbiota by enriching beneficial butyrate-producing bacteria (Lactobacillales, Faecalibacterium, Odoribacter, Roseburia, and Phascolarctobacterium) and reducing pathogenic Staphylococcus and Bilophila. Overall, dietary curcumin improved egg quality, antioxidant and immune functions, intestinal health, and microbial composition in late-laying hens.